Banknote evaluation is now commonly carried out and has become more critical in that the technology available to produce counterfeit bills is easily available and the quality of counterfeit bills has significantly increased. Currency of major countries continues to add different security features to their banknotes so that fraudulent banknotes are more easily detected and to act as a deterrent to the production of counterfeit bills.
Unattended currency accepting equipment such as vending machines, token dispensing machines, and other automated equipment include banknote acceptors. The banknote acceptors transport banknotes along an evaluation path and conduct various tests to predict the authenticity thereof. These banknote acceptors typically include optical sensors having an illumination source for illuminating a particular strip of the banknote as it moves through the evaluation path. The optical sensors include detectors for evaluating reflected light and can include filtering for light evaluation at different frequencies.
Banknote acceptors typically include a series of optical sensors that evaluate strips of a banknote to detect different security features provided at different positions on the banknote. Such evaluators often include different sensors for determining the magnetic, electrostatic, transparency and other characteristics of the banknote. Such banknote acceptors include sufficient optical sensors for evaluating critical aspects of different denominations of banknotes to be received and as such, the optical sensors are placed at different points across the evaluation path. There is a compromise between the number of sensors used to scan the surfaces of the banknote and the cost of the banknote acceptor. Full scanning of the banknote surface provides more data and can improve the prediction of whether the banknote is authentic or not, but the additional cost is difficult to justify, and furthermore, there is a time restraint for the effective analysis of the data.
Typically if the banknote moves slower along the banknote evaluation path or more time is provided to allow the banknote acceptor to consider all of the data, improvements in the prediction can be obtained. Unfortunately, from a customer point of view, the evaluation process must be essentially completed in real time; otherwise the transaction may be discontinued. In some applications it may be more profitable to accept additional risk in accepting a counterfeit banknote as opposed to an increase in the transaction time and improved evaluation of the banknote.
A further problem associated with existing banknote evaluation systems involves variations in the placement of the banknote within the evaluation path. The banknote can be fed to the evaluation path at a slight angle and/or the evaluation path can be larger than the width of the banknote and thus, the precise position of the strip being illuminated is within a range but is not precisely known. These factors also affect the accuracy of the banknote evaluation.
There continues to be a need to provide effective banknote evaluation quickly and at an acceptable cost.
The present invention provides an effective solution that addresses a number of these issues.